It may naturally be imagined, that, from mercury in this form, not only an escharotic power can be obtained, but that likewise, from its action as an antidote against the venereal virus, parts kept ulcerated, from the activity of this poison, may be healed. That, in some degree, it is fitted for this purpose likewise, is not to be doubted. But, to its employment in this way, its corrosive power is often an objection. In many cases, where it is required that an ulcer should be healed, a destruction of solid parts would be highly prejudicial. And when, in order to avoid this, the corrosive power of the mercury is diminished, from its being united with an ointment, the precipitate becomes liable to the same objection which was formerly urged against the efficacy of mercurial ointment. It is then in a state which does not admit of a ready union with the venereal virus. It may therefore, upon the whole, be concluded, that mercury in this form is principally useful in those cases, where, with the effect of an antidote against the venereal virus, it is necessary to conjoin an escharotic power. Mercury may be rendered saline by being united with other acids as well as the nitrous. These likewise are, in general, active preparations; but they do not possess a caustic power, at least in so high a degree as the nitrous preparations. Among the most active of the other saline preparations, are those prepared with the muriatic acid, and especially the corrosive sublimate. This is a mercurial preparation which, in many cases, may be employed to act immediately on parts affected by the venereal virus; it falls, therefore, to be considered also under this head. The stimulant power of corrosive sublimate is so great that it is never, even for external purposes, used in a solid form. But the _aqua phagedænica_ of the Edinburgh College, which is a solution of it in lime-water, is a mercurial preparation which has often been used externally, both in venereal and other foul ulcers. This form, however, contains so large a proportion of the mercury, that it is by much too stimulant for the greatest part of sores. A more dilute solution, in common spring-water, is free from this inconvenience, while, at the same time, it serves every purpose which can be expected from the other. The mercury in this solution is in a state sufficiently active to destroy the venereal virus, and is, at the same time, in a condition which will admit of a ready union with it. Good effects, therefore, might naturally be expected from it, especially as the form is such that it can with ease be applied.